To this end, Patents Nos. EP-A-286 586 and EP-A-286 586 disclose locking means of the aforementioned type, in which the lower end of a rocker is stopped on a lower portion of the boot, so as to force the upper of the boot to adopt an inclination, widely termed an "angle of overhang," which is essential for skiing. An upper end of the rocket has the shape of a press button designed to allow the release of the rocker when the skier wishes to straighten his leg or to walk.
When the skier wishes to resume skiing, he flexes the leg in order to bring the upper back into an inclined position. The locking action is then effected automatically once again, without any manual operation.
The disadvantage of this system lies in the fact that, during walking, for example in the released position, undersired automatic locking can occur, in particular when climbing a slope liable to cause a forward pivoting motion of the upper. This is due to the absence of a stable release position.
It will be easily understood that repeated manual release operations can prove tiresome for the skier.
To overcome this major, important disadvantage, proposals have been advanced suggesting manual means for releasing the aforementioned rocker which can immobilize the latter in a stable position corresponding to the release of the boot upper, as disclosed in FR-A 2 648 327. According to this document, the manual release means are constituted by a piece moving in vertical translational motion at the upper end of one of the rocker arms and capable of being manually actuated in an upward sliding movement, so as to extend this upper end of the rocker and to cooperate with a notch provided in the upper portion of a recess in the upper, in order to hold the rocker in the released position. A slide control assembly at the bottom of this mobile part has the effect of releasing this piece from the upper notch and of allowing it to pivot when acted upon by an elastic device, so that the lower end of said bascule is stopped on the aforementioned stop provided on the rear of the shell base, in operating position.
To permit manipulation of the mobile part in translational motion in either direction, this part has a projecting portion forming an outer gripping device, without which no control would be possible.
These locking means have a number of drawbacks, one of which lies in the fact that, whether the mobile device is in the locked or released position, the outer gripping device must always remain in a projecting configuration to permit access to it, and thus forms an aggressively protruding part capable of causing accidents. Another difficulty relates to design, since it becomes necessary to provide, on the one hand, a bascule which is relatively thick because it supports the mobile part and the gripping device attached to it, and, on the other hand, an upper notch to be cut in the upper.
Finally, as regards use, this system always requires two operations to produce a stable release of the boot upper, i.e., a rectilinear thrusting movement perpendicular to the upper in order to cause the rocker to pivot in a movement which releases its lower end from the stop, and a thrusting movement, also rectilinear and substantially parallel to the upper, so as to engage the mobile part beneath the upper notch.
This latter disadvantage does not occur in other conventional devices for immobilization of the upper of a boot, in which the locking, and indeed control, means are independent of the upper. For example, the ski boot described in French Patent Application No. 2 619 317 has upper-immobilization device comprising a stop means which is subjected to the continuous action of an elastic force which pushes it into its closed position, and which can be controlled in the open position in opposition to this force by means of a control mechanism located on the upper.
As illustrated, the stop means is housed in a recess in the upper, and takes the form of a double-arm lever pivoting around a pin mounted in the upper, while the control device is mounted so as to pivot externally to the upper, in proximity to the end of one of the arms of the stop lever.
In this type of construction, the release of the upper occurs as a result of an outer swinging movement of the control mechanism which, since it exerts pressure on the corresponding arm of the stop lever, produces the release of this lever from its stop on the shell base. To relock the upper in the skiing position, it then becomes necessary to bring the control mechanism back against the upper in order to permit the stop lever, under the effect of the elastic return force, to be placed in the engaged position in relation to its stop on the shell base.
As can be clearly seen, such an immobilization device has the disadvantage of protruding very appreciably on the rear part of the upper, and of requiring voluntary manipulation of the control mechanism in order to return to the locked position of the upper for the purpose of skiing.
The device for immobilization of a ski boot upper, as described in German Utility Model No. Gm 80 20 898 may also be cited as an example. In this document, the locking device incorporates a lever attached to the upper which can be stopped on an element of the boot shell. This lever is actuated using an external traveller capable of moving linearly and of acting angularly on the position of the lever from an end or central articulation point.
As in the preceding description, this device has the disadvantage of protruding permanently and variably from the rear portion of the upper, since the traveller can be moved in translational motion. Furthermore, this device always involves a voluntary operation performed by the skier, so as to travel from the released to the locked position for skiing. Here again, there is no possibility for a momentary release manoeuver and the opportunity for automatic relocking.